In nature, microbes face a spectacular array of stimuli that challenge their survival. Collectively, these stimuli exert a strong selective pressure for th evolution of sophisticated, rapid-response mechanisms that can efficiently maintain homeostasis through the modulation of functions of diverse biomolecules. Not surprisingly, biologists are interested in understanding how these mechanisms work, how they are regulated, and how they are integrated into the cellular regulatory circuits. The PI's laboratory studies the control of protein function by chemical modifications, with an emphasis on reversible lysine acylation (RLA). Ten years ago, the PI's group reported the first evidence of RLA in prokaryotes, a discovery that elicited a great deal of interest. In a short period of time, RLA has emerged as a posttranslational modification that rivals phosphorylation in terms of its breadth and impact on the dynamics of the complex metabolic network of the cell. In recent years, the PI's group has reported the impact of RLA on central cellular processes such as cell motility, gene expression, carbon metabolism, energy and coenzyme A homeostasis. The PI's laboratory studies the control of protein function by RLA. The long-term goal of the work supported by grant R01-GM062203 is to understand the contributions of RLA to cell function. The PI's group will continue to apply comprehensive genetic, molecular biological, biochemical, structural, and system-wide approaches to answer fundamental questions regarding the mechanism of RLA function. Work proposed herein seeks to: i) learn the molecular details of how acetyltransferases recognize their protein substrates; ii) gain insights into the mechanism of acetyltransferase function; iii) gain a better understanding of how proteins evolve to escape RLA control; and iv) define the regulatory circuit that integrates RLA into the complex metabolic network of the cell.